Hi all: I just got this working, so I thought of posting a small howto for the list :)
================================================ An apache instance (httpd) that serves http://localhost/examples/ where /examples is served by two Tomcat instances (if one is down/unavailable, then httpd decides to redirect requests to the second tomcat instances. What I've got working so far: - Session replication between the various Tomcat instances in the cluster. - In case one instance is not available, then apache sends new requests to the next instance. - When and instance comes back, it joins the cluster, receives session replication, and is ready to take over when required. What else is possible: - Load balance based on the number of requests already sent to a Tomcat instance - Configure timeouts, etc - More information at http://tomcat.apache.org/connectors-doc/reference/workers.html What's not possible: - If the first instance dies, then the second instance carries on processing from that point. To try this yourself: 1. Download and install Apache Tomcat 6.0.9 2. In server.xml, uncomment the tag for clustering 3. Edit the webapps/example/WEB-INF/web.xml to include the distributable tag <distributable/> 4. Create a copy of this Tomcat folder (say, Tomcat2) 5. Edit the server.xml in Tomcat2. Change all the port numbers. e.g. change the AJP port number to 8010 6. Download the file http://mirrors.24-7-solutions.net/pub/apache/tomcat/tomcat-connectors/jk/binaries/win32/jk-1.2.20/mod_jk-apache-2.2.3.so and save it as mod_jk.so at apache/modules folder. 7. Place the following contents in the file apache/conf/worker.properties # The advanced router LB worker worker.list=router,worker2,worker1 # Define a worker using ajp13 worker.worker1.port=8009 worker.worker1.host=localhost worker.worker1.type=ajp13 worker.worker1.lbfactor=1 # Define prefered failover node for worker1 worker.worker1.redirect=worker2 # Define another worker using ajp13 worker.worker2.port=8010 worker.worker2.host=localhost worker.worker2.type=ajp13 worker.worker2.lbfactor=1 worker.worker2.mount=/examples/* # Disable worker2 for all requests except failover worker.worker2.activation=disabled # Define the LB worker worker.router.type=lb worker.router.balance_workers=worker1,worker2 worker.list=jkstatus # Define a 'jkstatus' worker using status worker.jkstatus.type=status 8. Edit apache/conf/httpd.conf to include the following: LoadModule jk_module modules/mod_jk.so #AddModule mod_jk.c JkWorkersFile conf/worker.properties JkShmFile mod_jk.shm JkLogFile mod_jk.log JkLogLevel info JkLogStampFormat "[%a %b %d %H:%M:%S %Y] " JkMount /jkmanager/* jkstatus JkMount /examples/* router 9. Start the two Tomcat instances You should see some replication related messages in the console Feb 13, 2007 8:01:34 PM org.apache.catalina.ha.tcp.SimpleTcpCluster memberAdded INFO: Replication member added:org.apache.catalina.tribes.membership.MemberImpl[ tcp://Ramn.corporate.thoughtworks.com:4001,Ramn.corporate.thoughtworks.com,4001, alive=1016,id={99 34 -19 82 10 -107 64 51 -119 77 9 -117 -91 9 24 -9 }, payload ={}, command={}, domain={}, ] INFO: Manager [localhost#/examples]; session state send at 2/13/07 8:01 PM recei ved in 125 ms. 10. Restart the httpd web server Testing the session replication 1. Browse to http://localhost/examples/ 2. Try the Session examples for the servlet. 3. Set a variable into the session with a value 4. Stop the first Tomcat instance 5. Set another variable into the session. This time, the second Tomcat instance will serve the content You'll see that the first variable is still in the session. This is a sign that replication has been successful. 6. Restart the first instance, wait for it to enter the cluster and for the replication to happen INFO: Manager [localhost#/examples]; session state send at 2/13/07 8:01 PM recei ved in 125 ms. 7. Stop the second Tomcat instance. 8. Set another variable into the session. 9. You'll see that all the variables are still available. -- Sriram --------------------------------------------------------------------- To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
